Testbed Software

1. Testbed Software Presented by William List August 12, 2003

2. TUN/TAP • TUN virtual P2P device • Handles passing packets between kernel space and user space • TUN device read and writes to applications rather than physical media • TUN device handles IP packets • TAP device handles Ethernet frames • Not used

3. Ad-Hoc Support Library (ASL) • Captures packets in the kernel that do not have a valid destination • Packets are sent to /dev/tun0, and then forwarded to attached applications • Support re-insertion of packets into the kernel for forwarding • Uses a raw socket to avoid packet reprocessing by the kernel

4. ASL – Continued • Commands • open_route_request() • Sets up tun device, raw socket, and insert the route_check module into the kernel • route_add() and route_del() • Add or delete a route handled by tun0 • read_route_request() • Returns routing information in route_info • Select() used to identify events

5. ASL – Continued • More commands • route_discovery_done() • Tells ASL to release the waiting packets if route discovery was successful • query_route_idle_time() • Reads /proc/asl/route_check for last use of given destination • close_route_request() • Shutdown ASL

6. ASL Diagram

7. Wireless Tools • iwconfig • Provides configuration information for the wireless interface • iwconfig eth0 essid khop • iwconfig eth0 key none • iwconfig eth0 mode ad-hoc • iwconfig eth0 channel 3 • iwconfig eth0 rate 2M auto

8. Cardctl • Use to control the status of the wireless interface • cardctl scheme khop • “khop” must be an entry in /etc/wireless.opts • cardctl reset • Sometimes needed for changes to take effect • cardctl eject followed by re-insertion • An alternative for committing changes

9. Ip • Allows manipulation of the kernel routing table (alternative to route) • Show current routing entries • ip route show or route –n (easier to read) • Delete an entry • ip route del 192.168.0.1 • Add an entry • ip route add 192.168.0.1 dev eth0 • ip route add default via 192.168.0.1